Ad-hoc network power save system and method

ABSTRACT

Symmetrical and asymmetrical ad-hoc, wireless networks and a method for saving power in the same may include causing a first station to determine whether a second station has a master capability to buffer data traffic for the first station. A first station requests the second station to buffer the data traffic intended for the first station for a first predetermined period. The first station enters a first power save mode, and the second station buffers the data traffic for the first station for the first predetermined period. The first station exits the first power save mode after the first predetermined period and the second station sends the buffered data traffic to the first station. Both the first and second stations may have master capabilities, or only one of the first and second stations may have a master capability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/825,611, filled on Sep. 14, 2006. The disclosure of the aboveapplication is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a power save system in a network and,more particularly to a periodic power save system in an ad-hoc wirelessnetwork.

2. Related Art

A wireless network (e.g., Wi-Fi based on IEEE 802.11 standards) may becharacterized as an infrastructure mode network or an ad-hoc modenetwork depending on whether the stations within the wireless networkcan directly communicate with other stations in the network. FIG. 1(A)illustrates an example of an infrastructure mode wireless network, whichmay typically comprise an access point 2 and stations 4, 6 and 8. In theinfrastructure mode network, the stations 4, 6 and 8 are not configuredto directly communicate with each other, and any communication betweenthe stations 4, 6 and 8 must be channeled through the access point 2.

In contrast, an ad-hoc mode network allows each station to communicatedirectly with each other, as illustrated in FIG. 1(B). Thus, in thead-hoc mode wireless network, there is no central access pointcontrolling communication among the stations 4, 6 and 8. Ad-hoc devicesare configured to communicate only with other ad-hoc devices, and theyare not able to communicate with any infrastructure devices or any otherdevices connected to a wired network.

Considering that a significant portion of the Wi-Fi devices are portabledevices (e.g., cellular phones, portable gaming devices, wirelessheadsets, wireless headphones, wireless speakers and the like), powerconsumption has become an important issue for the Wi-Fi devices. Thishas led the IEEE to standardize the infrastructure mode network powersave protocol. However, due to the decentralized nature of ad-hoc modenetworks, it is much more difficult and complicated to implement powersave algorithms when there is no central access point that dictates allthe decisions related to power consumption in the network.

SUMMARY OF THE INVENTION

The invention allows ad-hoc network devices to enter a power save mode.The invention also provides for power consumption decisions to be madein an ad-hoc network to improve implementation of power save algorithms.Other advantages and benefits of the invention are apparent from thediscussion herein.

Accordingly, in one aspect of the invention, a method for saving powerin an ad-hoc network including first and second stations each having awireless capability to directly communicate with each other includesissuing a request to the second station to buffer data traffic intendedfor the first station for a first predetermined period, granting therequest to buffer data traffic, causing the first station to enter afirst power save mode for the first predetermined period, and enablingthe second station to buffer data traffic intended for the first stationfor the first predetermined period.

The method may further include causing the first station to exit thefirst power save mode after the first predetermined period elapses, andsending the buffered data traffic to the first station. Sending thebuffered data traffic may include sending the buffered data traffic fromthe second station to the first station. The method may further includecausing the first and second stations to simultaneously enter a secondpower save mode for a second period time. The method may further includeadvertising a master capability of the second station to buffer datatraffic intended for the first station. The method may further includecausing the second station to exit the second power save mode before thefirst station exits the second power save mode. The ad-hoc network maybe a wireless network using protocol selected from the group consistingof IEEE 802.11 standards and Bluetooth standards. The method may furtherinclude determining whether the second station has a capability tobuffer data traffic intended for the first station. The method mayfurther include issuing a request to the first station to buffer datatraffic intended for the second station for a second predeterminedperiod, granting the request to buffer data traffic intended for thesecond station, causing the second station to enter a second power savemode for the second predetermined period, and enabling the first stationto buffer the data traffic intended for the second station for thesecond predetermined period. The method may further include causing thesecond station to exit the second power save mode after the secondpredetermined period elapses, and sending the buffered data traffic tothe second station. Sending the buffered data traffic to the secondstation may include sending the buffered data traffic from the firststation to the second station. The method may further includedetermining whether the first station has a capability to buffer datatraffic intended for the second station. The method may further includepreventing the first station from entering the first power save mode ifthe second station requests the first station to buffer the data trafficintended for the second station, and preventing the second station fromentering the second power save mode if the first station requests thesecond station to buffer the data traffic intended for the firststation. The method may further include preventing the first stationfrom entering the first power save mode occurs if the request isreceived within a predetermined period of time from when the firststation sends such a request, and preventing the second station fromentering the second power save mode occurs if the request is receivedwithin a predetermined period of time from when the second station sendssuch a request. The method may further include causing the slave stationto exit the power save mode after the predetermined period elapses, andcausing the master station to send the buffered data traffic to theslave station. The method may further include advertising a mastercapability of the master station to buffer data traffic intended for anyof the plurality of stations in the ad-hoc network, and determining ifthe master station has the master capability to buffer data trafficintended for one of the plurality of stations. The ad-hoc network may bea wireless network using a protocol selected from the group consistingof IEEE 802.11 standards and Bluetooth standards.

According to another aspect of the invention, a method for saving powerin an ad-hoc network including a plurality of stations, the plurality ofstations including a master station and at least one slave stationincapable of buffering traffic for other stations, each station having awireless capability to directly communicate with other stations,includes issuing a request to the master station to buffer data trafficintended for the slave station for a predetermined period, granting therequest to buffer data traffic, causing the slave station to enter apower save mode for the predetermined period, and enabling the masterstation to buffer data traffic intended for the slave station for thepredetermined period.

The first station has a master capability to buffer data trafficintended for other stations in the ad-hoc network for a secondpredetermined period and may be configured to grant a request from thesecond station to allow the second station to enter a second power savemode, and wherein the second station may be configured to determine ifthere may be any station having the master capability in the ad-hocnetwork. The second station may enter the second power save mode for thesecond predetermined period when the first station grants the requestfrom the second station, and the first station sends the buffered datatraffic to the second station after the second predetermined periodelapses. The first station may be configured not to enter the firstpower save mode if the second station requests the first station tobuffer the data traffic intended for the second station, and the secondstation may be configured not to enter the second power save mode if thefirst station requests the second station to buffer the data trafficintended for the first station. The first station may not enter thefirst power save mode if the request is received within a predeterminedperiod of time from when the first station sends such a request, andwherein the second station may not enter the first power save mode ifthe request is received within a predetermined period of time from whenthe second station sends such a request. The master and slave stationsmay be configured to simultaneously enter a second power save mode for asecond period time. The master station may be configured to exit thesecond power save mode before the slave station exits the second powersave mode. The ad-hoc network may be a wireless network using a protocolselected from the group consisting of IEEE 802.11 standards andBluetooth standards.

In yet another aspect of the invention, an ad-hoc network includes afirst station having wireless communication capabilities and configuredto determine if there is any station in the ad-hoc network having amaster capability to buffer data traffic intended for other stations inthe ad-hoc network for a first predetermined period, the second stationhaving wireless communication capabilities and the master capability andconfigured to grant a request from said first station to allow saidfirst station to enter a first power save mode, and wherein the firststation enters the first power save mode for the first predeterminedperiod when the second station grants the request and the second stationsends the buffered data traffic to the first station after the firstpredetermined period elapses A system for saving power in an ad-hocnetwork including first and second stations each having a wirelesscapability to directly communicate with each other, the system furtherincludes means for issuing a request to the second station to bufferdata traffic intended for the first station for a first predeterminedperiod, means for granting the request to buffer data traffic, means forcausing the first station to enter a first power save mode for the firstpredetermined period, and means for enabling the second station tobuffer data traffic intended for the first station for the firstpredetermined period.

A machine-readable medium including stored instructions, which, whenexecuted by a processor cause the processor to implement power saving inan ad-hoc network having a plurality of stations, the instructionsincluding instructions for determining whether a first one of thestations has a capability to buffer data traffic intended for a secondstation, instructions for requesting the at least one station to bufferdata traffic intended for the second station for a first predeterminedperiod, instructions for granting a request to buffer data trafficintended for the second station, instructions for causing the secondstation to enter a first power save mode for the first predeterminedperiod, and instructions for enabling the first one station to bufferdata traffic intended for the second station for a second predeterminedperiod, instructions for causing the second station to exit the firstpower save mode after the first predetermined period elapses, andinstructions for sending the buffered data traffic to the secondstation.

Additional features, advantages, and embodiments of the invention may beset forth or apparent from consideration of the following detaileddescription, drawings, and claims. Moreover, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are exemplary and intended to provide further explanationwithout limiting the scope of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the detailed description serve to explain the principlesof the invention. No attempt is made to show structural details of theinvention in more detail than may be necessary for a fundamentalunderstanding of the invention and the various ways in which it may bepracticed. In the drawings:

FIGS. 1(A) and 1(B) illustrate an example of an infrastructure modenetwork and ad-hoc mode network, respectively;

FIG. 2(A) and 2(B) illustrate examples of a symmetrical ad-hoc network;

FIG. 3(A), 3(B) and 3(C) illustrate examples of a asymmetrical ad-hocnetwork;

FIG. 4(A) is a flow chart for a power save scheme in a symmetricalad-hoc network constructed according to the principles of the invention;and

FIG. 4(B) is a flow chart for a power save scheme in an asymmetricalad-hoc network constructed according to the principles of the invention.

FIGS. 5-12 show various exemplary implementations of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the invention and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting embodiments and examples that are described and/orillustrated in the accompanying drawings and detailed in the followingdescription. It should be noted that the features illustrated in thedrawings are not necessarily drawn to scale, and features of oneembodiment may be employed with other embodiments as the skilled artisanwould recognize, even if not explicitly stated herein. Descriptions ofwell-known components and processing techniques may be omitted so as tonot unnecessarily obscure the embodiments of the invention. The examplesused herein are intended merely to facilitate an understanding of waysin which the invention may be practiced and to further enable those ofskill in the art to practice the embodiments of the invention. Forexample, the invention is described in terms of Wi-Fi network based onIEEE 802.11 standard, but it will be understood that the invention isnot so limited. The invention may be broadly applicable to any ad-hocmode wireless network and other types of wireless networks that haveappropriate features and characteristics. Accordingly, the examples andembodiments herein should not be construed as limiting the scope of theinvention, which is defined solely by the appended claims and applicablelaw. Moreover, it is noted that like reference numerals representsimilar parts throughout the several views of the drawings.

The invention relates to periodic power save protocols for ad-hocnetworks. Different devices within the ad-hoc network can take on therole of a master while the other slave devices enter a power save mode.The master device receives data for the other devices and sends thebuffered data when those slave devices wake up. This protocol allows forpower savings among the devices. Various aspects of the invention willnow be described in greater detail below.

FIGS. 2(A), 2(B), 3(A), 3(B) and 3(C) illustrate examples of an ad-hocmode network configuration. Depending on similarity of capabilitiesamong the devices (i.e., stations, nodes or the like) in the network,the ad-hoc mode network may be characterized as a symmetrical ad-hocmode network or an asymmetrical ad-hoc mode network. FIGS. 2(A) and 2(B)illustrate examples of the symmetrical ad-hoc mode network, in which thedevices may have similar capabilities, such as, for example, processingpower, memory, battery life or the like. In particular, FIG. 2(A)illustrates two walkie-talkies or cellular phones 12 and 14 withidentical or substantially the same capabilities connected via an ad-hocmode network. This connection allows real-time multi-user voicecommunication via the ad-hoc mode network. When the devices 12 and 14are not in use, it may be necessary to turn off one or both devices tosave power. Since there is no central access point to carry out a powersave mode, a power save protocol may be carried out on all devices inthe network without overburdening any particular device. For example,each of the devices 12 and 14 may alternatively take charge by acting asa master device that carries out power save algorithms in the network.

Similarly, FIG. 2(B) illustrates two identical portable gaming devices16 and 18 (e.g., Sony™ PSP™ or the like) connected to each other via anad-hoc mode network. This connection may provide real-time multi-playergaming experiences for those using the portable gaming devices 16 and18. When the devices 16 and 18 are not being used, the devices 16 and 18may communicate with each other to decide which device will take chargeas a “master” to carry out a power save protocol for the network. The“master” device may allow other devices (i.e., slaves) in the network toenter a power save mode and buffer data traffic for the slave devices,which will be also described below in detail. It should be understoodthat walkie-talkies, cell phones and gaming devices are merelyillustrative of the type of devices that may be connected in asymmetrical, ad-hoc network.

FIGS. 3(A), 3(B) and 3(B) illustrate examples of the asymmetrical ad-hocmode network configuration, in which the ad-hoc devices have differentcapabilities. For example, FIG. 3(A) illustrates an asymmetrical ad-hocmode network including a cellular phone 20 and a wireless headset 22.Typically, the wireless headset 22 is provided with significantly lesscapabilities than the cellular phone 20 and may not be able to carry outthe power save algorithms for the ad-hoc network. In this case, thepower save protocol may exploit the capabilities of the cellular phone20, which may permanently take charge as a master while the headset 22permanently operates as a slave in this situation. Similarly, FIG. 3(B)illustrates a PC 24 and a wireless headphone 26 connected to each othervia an ad-hoc mod network, wherein the PC 24 operates as the masterwhile the wireless headphone 26 operates as the slave in carrying outthe power save mode. In FIG. 3(C), an audio device 30 with morecapabilities may carry out the power save mode as a permanent master towireless speakers 32. Again, these examples are merely illustrative ofthe type of devices that may be connected in an asymmetrical, ad-hocnetwork.

FIG. 4(A) illustrates a flow chart for a power save scheme in asymmetrical ad-hoc network constructed according to the principles ofthe invention. As mentioned above, in a symmetrical ad-hoc mode network,each device may have capabilities to carry out power save algorithms inthe network as a master. Thus, it is assumed that stations A and B(e.g., walkie-talkies 12 and 14 in FIG. 2(A), respectively) are bothequally capable of carrying out the power save algorithms withoutoverburdening the other one. As shown in steps 40 and 42, stations 12and 14 both advertise their master capabilities to other stations in thenetwork. The master capabilities may include an ability to buffer datadesignated for other stations in the network that are in a sleep (powersave) mode. After confirming that station B has master capabilities,station A may send a power save enter request to station B, as shown instep 44. The power save enter request may be included in an uplink IEEEaction management frame of station A's beacon that is sent to station B.The frame may include information about the sleep period of station A.The power save enter request may be included in an uplink IEEE actionmanagement frame sent from slave to master. The capability to implementthis protocol may be advertised in the station beacons and proberesponses. The power save enter request/response may be sent using IEEEAction Management frames. Further, the power save enter request mayinclude information about the slave station's frequency of wake-ups(referred to as sleep period), while the power save enter response mayinclude information about a number of service periods the master maybuffer traffic for slave.

It is possible that both stations A and B send their respective powersave enter requests to each other. To avoid the conflict, each stationmay be configured to stay in a full power mode when the request isreceived from other stations. Each station may then compute a randomback-off and re-attempt to enter the power save mode when the back-offexpires or stay in full power mode as the master if other station'sback-off expires earlier.

Upon accepting the request from station A, station B becomes the masterand station A becomes the slave. As shown in step 46, station B may senda power save enter response to station A. The power save enter responsemay be included in an IEEE action management frame. The power save enterresponse may contain the maximum number of service periods during whichthe master station B will buffer data traffic for slave station A.According to an embodiment of the invention, a service period may bedefined as the period between receiving an uplink trigger from slavestation A to the point where master station B sends an end of serviceperiod (EOSP) indication. Each uplink frame with a trigger bit set fromslave station A may be counted as one service period by master stationB. For Wi-Fi multi-media (WMM) applications, for example, the WWM EOSPbit in the quality of service (QOS) information field may be used as thetrigger bit by slave station in the uplink direction. For non-WMMapplications, for example, the “more-data” bit in the IEEE 802.11 framecontrol field may be used as the trigger bit.

In step 46, after receiving the power save enter response from masterstation B, slave station A may enter power save mode as shown in step48. Master station B may start buffering data traffic for slave stationA, as shown in step 50. While in the power save mode, slave station Amay not beacon and advertise its capability as a master. Every timeslave station A wakes up, it may send an uplink trigger frame to masterstation B with the trigger bit “set.” Slave station A may send exactlyone trigger frame in every wake-up period. If slave station A has morethan one frame in every wake-up period, slave station A may transmitsubsequent frames with trigger bit “unset.” If slave station A has nouplink data to send, it may send a “null” uplink trigger frame withtrigger bit set. Also, all uplink frames from slave station A may havethe power management bit set to “1” in the IEEE 802.11 frame controlfield. Master station B, in turn, may respond to the trigger frame withdownlink data buffered for slave station A. The last downlink frame frommaster station B may the EOSP bit set. For WMM applications, the WMMEOSP bit in the QOS information field may be used by master station B inthe downlink direction to mark EOSP. For non-WMM applications, the“more-data” bit in the IEEE 802.11 frame control field may be used asthe EOSP indication. If no downlink data has been buffered for slavestation A, master station B may send a null data frame with the EOSP bitset. Also, in one example, the system may be configured so that theuplink frames sent from slave station A with the trigger bit unset maynot cause master station B to empty a power save queue for therespective slave station.

After the maximum number of service periods permitted by master stationB is reached, master station B may stop buffering data traffic for slavestation A. Slave station A may end power save mode in step 52. The datais buffered by master station B and forwarded to slave station A in step54. Slave station A and master station B may enter the full power modeby resuming beaconing and advertising their capability as a masterstation, as shown in steps 56 and 58. Both stations A and B then maycompute a random back-off and attempt to become slaves on back-offexpiry. The steps shown in FIG. 4(A) may be repeated. Since each stationmay rotate through the role of a slave or master, power consumptionissues on all stations in the network may be greatly improved withoutoverburdening a particular station. For example, assuming that eachstation spends equal time in the master and slave roles, the power saveprotocol may reduce the power consumption for the slave stations up toabout 75%. Further, the protocol may reduce the power consumption forboth master and slave stations up to about 38% compared to the fullpower mode. The power saving may increase as the number of slavestations increases.

FIG. 4(B) illustrates a flow chart for a power save scheme in anasymmetrical ad-hoc network constructed according to the principles ofthe invention. For example, the asymmetrical ad-hoc network may includethe cellular phone 20 as the master and the wireless headset 22illustrated in FIG. 3(A). As mentioned above, in the asymmetrical ad-hocnetwork, only one station may have the master capabilities. Thus, step60 of advertising the master capabilities and the master/slave powersave enter request/response steps 62 and 64 (i.e., master/slavehandshake) are implemented. For example, the master station may return0xFFFF in the maximum service period field as the “master indefinite”indication. Some implementations with pre-provisioned master/slaveconfigurations may bypass the master/slave handshake among the stationsas their roles may have been already decided at the production stage.Other than those differences, the power save protocol illustrated inFIG. 4(B) may perform steps similar to the steps performed for thesymmetrical ad-hoc power save mode shown in FIG. 4(A). For example,after executing the master/slave handshake shown in steps 62 and 64, theslave station 22 may enter the power save mode at step 66 while themaster station 20 may buffer the data traffic for the slave station 22at step 68. When the slave station 22 wakes up from the power save modeat step 70, the master station 20 may send the buffered data traffic tothe slave station 20 at step 72. If the slave station 22 is notfrequently used, power save may be greatly increased by allowing theslave station 22 to enter the power save mode.

In order to further improve power saving, the master station 20 may usethe sleep period of the slave station 22 to enter the power save modeafter sending a downlink frame with the EOSP bit set. For example, uponreceiving an uplink frame from the slave station 22 with the trigger bitset, the master station 20 may start a sleep clock timer with a timeoutset to expire at a certain point before the slave station 22 wakes up.The sleep clock timer may include an offset that may account for anytiming errors in the sleep clock to ensure the master station 20 wakesup before the next slave wakeup. The master station 20 may exchange datawith the EOSP bit set in the last downlink frame to the slave station22. After sending the frame with the EOSP bit set, the master and slavestations both may enter the power save mode. The slave station 22 may berequired not to transmit any frames after receiving the downlink withthe EOSP bit set. In this case, if both the master and slave stationshave 75% power savings in the power save mode, the overall system may beable to save power up to 75%.

Referring now to FIGS. 5, 6, 7, 8, 9, 10, 11 and 12, various exemplaryapplications of the invention are shown. Referring to FIG. 5, theinvention may be embodied in a hard disk drive 500. The invention mayimplement either or both signal processing and/or control circuits,which are generally identified in FIG. 5 at 502. In someimplementations, signal processing and/or control circuit 502 and/orother circuits (not shown) in HDD 500 may process data, perform codingand/or encryption, perform calculations, and/or format data that isoutput to and/or received from a magnetic storage medium 506.

HDD 500 may communicate with a host device (not shown) such as acomputer, mobile computing devices such as personal digital assistants,cellular phones, media or MP3 players and the like, and/or other devicesvia one or more wired or wireless communication links 508. HDD 500 maybe connected to memory 509, such as random access memory (RAM), a lowlatency nonvolatile memory such as flash memory, read only memory (ROM)and/or other suitable electronic data storage.

Referring first to FIG. 6, the invention may be embodied in a digitalversatile disc (DVD) drive 511. The invention may implement either orboth signal processing and/or control circuits, which are generallyidentified in FIG. 6 at 512, and/or mass data storage 518 of the DVDdrive 511. Signal processing and/or control circuit 513 and/or othercircuits (not shown) in the DVD 511 may process data, perform codingand/or encryption, perform calculations, and/or format data that is readfrom and/or data written to an optical storage medium 516. In someimplementations, signal processing and/or control circuit 512 and/orother circuits (not shown) in DVD 511 can also perform other functionssuch as encoding and/or decoding and/or any other signal processingfunctions associated with a DVD drive.

DVD drive 511 may communicate with an output device (not shown) such asa computer, television or other device via one or more wired or wirelesscommunication links 517. DVD 511 may communicate with mass data storage518 that stores data in a nonvolatile manner. DVD 511 may be connectedto memory 519, such as RAM, ROM, low latency nonvolatile memory such asflash memory, and/or other suitable electronic data storage.

Referring now to FIG. 7, the invention may be embodied in a highdefinition television (HDTV) 520. The invention may implement either orboth signal processing and/or control circuits, which are generallyidentified in FIG. 7 at 522, a WLAN interface and/or mass data storageof the HDTV 520. HDTV 520 receives HDTV input signals in either a wiredor wireless format and generates HDTV output signals for a display 526.In some implementations, the signal processing circuit and/or controlcircuit 522 and/or other circuits (not shown) of HDTV 520 may processdata, perform coding and/or encryption, perform calculations, formatdata and/or perform any other type of HDTV processing that may berequired.

HDTV 520 may communicate with a mass data storage 527 that stores datain a nonvolatile manner such as optical and/or magnetic storage devices.At least one DVD may have the configuration shown in FIG. 6. HDTV 520may be connected to a memory 528 such as RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage. HDTV 520 also may support connections with a WLAN via aWLAN network interface 529.

Referring now to FIG. 8, the invention may be implemented in a controlsystem of a vehicle 530, a WLAN interface and/or mass data storage ofthe vehicle control system. In some implementations, the inventionimplements a powertrain control system 532 that receives inputs from oneor more sensors 536 such as temperature sensors, pressure sensors,rotational sensors, airflow sensors and/or any other suitable sensorsand/or that generates one or more output control signals from an output538 such as engine operating parameters, transmission operatingparameters, and/or other control signals.

The invention may also be embodied in other control systems 540 ofvehicle 530. Control system 540 may likewise receive signals from inputsensors 542 and/or output control signals to one or more output devices544. In some implementations, control system 540 may be part of ananti-lock braking system (ABS), a navigation system, a telematicssystem, a vehicle telematics system, a lane departure system, anadaptive cruise control system, a vehicle entertainment system such as astereo, DVD, compact disc and the like. Still other implementations arecontemplated.

Powertrain control system 532 may communicate with mass data storage 546that stores data in a nonvolatile manner. Mass data storage 546 mayinclude optical and/or magnetic storage devices for example hard diskdrives HDD and/or DVDs. At least one DVD may have the configurationshown in FIG. 6. Powertrain control system 532 may be connected tomemory 547 such as RAM, ROM, low latency nonvolatile memory such asflash memory and/or other suitable electronic data storage. Powertraincontrol system 532 also may support connections with a WLAN via a WLANnetwork interface 548. The control system 540 may also include mass datastorage, memory and/or a WLAN interface (all not shown).

Referring now to FIG. 9, the invention may be embodied in a cellularphone 550 that may include a cellular antenna 551. The invention mayimplement either or both signal processing and/or control circuits,which are generally identified in FIG. 9 at 552, a WLAN interface and/ormass data storage of the cellular phone 550. In some implementations,cellular phone 550 includes a microphone 556, an audio output 558 suchas a speaker and/or audio output jack, a display 560 and/or an inputdevice 562 such as a keypad, pointing device, voice actuation and/orother input device. Signal processing and/or control circuits 552 and/orother circuits (not shown) in cellular phone 550 may process data,perform coding and/or encryption, perform calculations, format dataand/or perform other cellular phone functions.

Cellular phone 550 may communicate with a mass data storage 564 thatstores data in a nonvolatile manner such as optical and/or magneticstorage devices for example hard disk drives HDD and/or DVDs. At leastone DVD may have the configuration shown in FIG. 6. Cellular phone 550may be connected to a memory 566 such as RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage. Cellular phone 550 also may support connections with aWLAN via a WLAN network interface 568.

Referring now to FIG. 10, the invention may be embodied in a set top box580. The invention may implement either or both signal processing and/orcontrol circuits, which are generally identified in FIG. 10 at 584, aWLAN interface and/or mass data storage of the set top box 580. Set topbox 580 receives signals from a source such as a broadband source andoutputs standard and/or high definition audio/video signals suitable fora display 588 such as a television and/or monitor and/or other videoand/or audio output devices. Signal processing and/or control circuits584 and/or other circuits (not shown) of the set top box 580 may processdata, perform coding and/or encryption, perform calculations, formatdata and/or perform any other set top box function.

Set top box 580 may communicate with mass data storage 590 that storesdata in a nonvolatile manner. Mass data storage 590 may include opticaland/or magnetic storage devices for example hard disk drives HDD and/orDVDs. At least one DVD may have the configuration shown in FIG. 6. Settop box 580 may be connected to memory 594 such as RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage. Set top box 580 also may support connections with a WLANvia a WLAN network interface 596.

Referring now to FIG. 11, the invention may be embodied in a mediaplayer 600. The invention may implement either or both signal processingand/or control circuits, which are generally identified in FIG. 11 at604, a WLAN interface and/or mass data storage of the media player 600.In some implementations, media player 600 includes a display 607 and/ora user input 608 such as a keypad, touchpad and the like. In someimplementations, media player 600 may employ a graphical user interface(GUI) that typically employs menus, drop down menus, icons and/or apoint-and-click interface via display 607 and/or user input 608. Mediaplayer 600 further includes an audio output 609 such as a speaker and/oraudio output jack. Signal processing and/or control circuits 604 and/orother circuits (not shown) of media player 600 may process data, performcoding and/or encryption, perform calculations, format data and/orperform any other media player function.

Media player 600 may communicate with mass data storage 610 that storesdata such as compressed audio and/or video content in a nonvolatilemanner. In some implementations, the compressed audio files includefiles that are compliant with MP3 format or other suitable compressedaudio and/or video formats. The mass data storage may include opticaland/or magnetic storage devices for example hard disk drives HDD and/orDVDs. At least one DVD may have the configuration shown in FIG. 6. Mediaplayer 600 may be connected to memory 614 such as RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage. Media player 600 also may support connections with a WLANvia a WLAN network interface 616.

Referring to FIG. 12, the invention may be embodied in a Voice overInternet Protocol (VoIP) phone 650 that may include an antenna 618. Theinvention may implement either or both signal processing and/or controlcircuits, which are generally identified in FIG. 12 at 604, a wirelessinterface and/or mass data storage of the VoIP phone 650. In someimplementations, the VoIP phone 650 includes, in part, a microphone 610,an audio output 612 such as a speaker and/or audio output jack, adisplay monitor 614, an input device 616 such as a keypad, pointingdevice, voice actuation and/or other input devices, and a WirelessFidelity (Wi-Fi) communication module 608. Signal processing and/orcontrol circuits 604 and/or other circuits (not shown) in VoIP phone 650may process data, perform coding and/or encryption, performcalculations, format data and/or perform other VoIP phone functions.

VoIP phone 650 may communicate with mass data storage 602 that storesdata in a nonvolatile manner such as optical and/or magnetic storagedevices, for example hard disk drives HDD and/or DVDs. At least one DVDmay have the configuration shown in FIG. 6. The VoIP phone 650 may beconnected to memory 606, which may be a RAM, ROM, low latencynonvolatile memory such as flash memory and/or other suitable electronicdata storage. The VoIP phone 650 may be configured to establishcommunications link with a VoIP network (not shown) via Wi-Ficommunication module 608. Still other implementations in addition tothose described above are contemplated.

In accordance with various embodiments of the invention, the methodsdescribed herein are intended for operation with dedicated hardwareimplementations including, but not limited to, semiconductors,application specific integrated circuits, programmable logic arrays, andother hardware devices constructed to implement the methods and modulesdescribed herein. Moreover, various embodiments of the inventiondescribed herein are intended for operation with as software programsrunning on a computer processor. Furthermore, alternative softwareimplementations including, but not limited to, distributed processing orcomponent/object distributed processing, parallel processing, virtualmachine processing, any future enhancements, or any future protocol canalso be used to implement the methods described herein.

It should also be noted that the software implementations of theinvention as described herein are optionally stored on a tangiblestorage medium, such as: a magnetic medium such as a disk or tape; amagneto-optical or optical medium such as a disk; or a solid statemedium such as a memory card or other package that houses one or moreread-only (non-volatile) memories, random access memories, or otherre-writable (volatile) memories. A digital file attachment to email orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the invention is considered to include a tangiblestorage medium or distribution medium, as listed herein and includingart-recognized equivalents and successor media, in which the softwareimplementations herein are stored.

While the invention has been described in terms of exemplaryembodiments, those skilled in the art will recognize that the inventioncan be practiced with modifications in the spirit and scope of theappended claims. By way of example, the stations of the inventions maybe any device capable of wireless communication and standards other thanthe IEEE 802.11 standard may be used to implement the invention, such asBluetooth and similar standards. These examples given above are merelyillustrative and are not meant to be an exhaustive list of all possibledesigns, embodiments, applications or modifications of the invention.

1. A method for saving power in an ad-hoc network including first andsecond stations each having a wireless capability to directlycommunicate with each other, said method comprising: issuing a requestto the second station to buffer data traffic intended for the firststation for a first predetermined period; granting the request to bufferdata traffic; causing the first station to enter a first power save modefor the first predetermined period; and enabling the second station tobuffer data traffic intended for the first station for the firstpredetermined period.
 2. The method of claim 1 further comprising:causing the first station to exit the first power save mode after thefirst predetermined period elapses; and sending the buffered datatraffic to the first station.
 3. The method of claim 2, wherein sendingthe buffered data traffic comprises sending the buffered data trafficfrom the second station to the first station.
 4. The method of claim 2,further comprising causing the first and second stations tosimultaneously enter a second power save mode for a second period time.5. The method of claim 4, further comprising advertising a mastercapability of the second station to buffer data traffic intended for thefirst station.
 6. The method of claim 4, further comprising causing thesecond station to exit the second power save mode before the firststation exits the second power save mode.
 7. The method of claim 1,wherein the ad-hoc network is a wireless network using protocol selectedfrom the group consisting of IEEE 802.11 standards and Bluetoothstandards.
 8. The method of claim 1, further comprising determiningwhether the second station has a capability to buffer data trafficintended for the first station.
 9. The method of claim 1, furthercomprising: issuing a request to the first station to buffer datatraffic intended for the second station for a second predeterminedperiod; granting the request to buffer data traffic intended for thesecond station; causing the second station to enter a second power savemode for the second predetermined period; and enabling the first stationto buffer the data traffic intended for the second station for thesecond predetermined period.
 10. The method of claim 9, furthercomprising: causing the second station to exit the second power savemode after the second predetermined period elapses; and sending thebuffered data traffic to the second station.
 11. The method of claim 10,wherein sending the buffered data traffic to the second stationcomprises sending the buffered data traffic from the first station tothe second station.
 12. The method of claim 9, further comprisingdetermining whether the first station has a capability to buffer datatraffic intended for the second station.
 13. The method of claim 9,further comprising: preventing the first station from entering the firstpower save mode if the second station requests the first station tobuffer the data traffic intended for the second station; and preventingthe second station from entering the second power save mode if the firststation requests the second station to buffer the data traffic intendedfor the first station.
 14. The method of claim 13, wherein preventingthe first station from entering the first power save mode if the requestis received within a predetermined period of time from when the firststation sends such a request; and preventing the second station fromentering the second power save mode occurs if the request is receivedwithin a predetermined period of time from when the second station sendssuch a request.
 15. A method for saving power in an ad-hoc networkincluding a plurality of stations, the plurality of stations including amaster station and at least one slave station incapable of bufferingtraffic for other stations, each station having a wireless capability todirectly communicate with other stations, said method comprising:issuing a request to the master station to buffer data traffic intendedfor the slave station for a predetermined period; granting the requestto buffer data traffic; causing the slave station to enter a power savemode for the predetermined period; and enabling the master station tobuffer data traffic intended for the slave station for the predeterminedperiod.
 16. The method of claim 15, further comprising: causing theslave station to exit the power save mode after the predetermined periodelapses; and causing the master station to send the buffered datatraffic to the slave station.
 17. The method of claim 15, furthercomprising: advertising a master capability of the master station tobuffer data traffic intended for any of the plurality of stations in thead-hoc network; and determining if the master station has the mastercapability to buffer data traffic intended for one of the plurality ofstations.
 18. The method of claim 15, wherein the ad-hoc network is awireless network using a protocol selected from the group consisting ofIEEE 802.11 standards and Bluetooth standards.
 19. An ad-hoc network,comprising: a first station having wireless communication capabilitiesand configured to determine if there is any station in the ad-hocnetwork having a master capability to buffer data traffic intended forother stations in the ad-hoc network for a first predetermined period; asecond station having wireless communication capabilities and the mastercapability and configured to grant a request from said first station toallow said first station to enter a first power save mode, and whereinsaid first station enters the first power save mode for the firstpredetermined period when said second station grants the request andsaid second station sends the buffered data traffic to said firststation after the first predetermined period elapses.
 20. The ad-hocnetwork of claim 19, wherein said first station has a master capabilityto buffer data traffic intended for other stations in the ad-hoc networkfor a second predetermined period and is configured to grant a requestfrom said second station to allow said second station to enter a secondpower save mode, and wherein said second station is configured todetermine if there is any station having the master capability in thead-hoc network.
 21. The ad-hoc network of claim 20, wherein said secondstation enters the second power save mode for the second predeterminedperiod when said first station grants the request from said secondstation, and said first station sends the buffered data traffic to saidsecond station after the second predetermined period elapses.
 22. Thead-hoc network of claim 21, wherein said first station is configured notto enter the first power save mode if said second station requests saidfirst station to buffer the data traffic intended for said secondstation, and said second station is configured not to enter the secondpower save mode if said first station requests said second station tobuffer the data traffic intended for said first station.
 23. The methodof claim 22, wherein said first station not entering the first powersave mode occurs if the request is received within a predeterminedperiod of time from when said first station sends such a request; andwherein said second station not entering the first power save modeoccurs if the request is received within a predetermined period of timefrom when said second station sends such a request.
 24. The ad-hocnetwork of claim 19, wherein the ad-hoc network is a wireless networkusing a protocol selected from the group consisting of IEEE 802.11standards and Bluetooth standards.
 25. An ad-hoc network comprising: amaster station having wireless communication capabilities and a mastercapability to buffer data traffic intended for other stations in thead-hoc network for a predetermined period; at least one slave stationincapable of buffering the traffic for other stations having wirelesscommunication capabilities and configured to determine whether themaster station is available in the ad-hoc network; and wherein saidslave station enters a power save mode for the predetermined period whensaid master station grants a request issued by said slave station toallow said slave station to enter the power save mode, and said masterstation sends the buffered data traffic to said slave station after thepredetermined period elapses.
 26. The ad-hoc network of claim 25,wherein said master and slave stations are configured to simultaneouslyenter a second power save mode for a second period time.
 27. The ad-hocnetwork of claim 26, wherein said master station is configured to exitthe second power save mode before said slave station exits the secondpower save mode.
 28. The ad-hoc network of claim 25, wherein the ad-hocnetwork is a wireless network using a protocol selected from the groupconsisting of IEEE 802.11 standards and Bluetooth standards.
 29. Asystem for saving power in an ad-hoc network including first and secondstations each having a wireless capability to directly communicate witheach other, said system comprising: means for issuing a request to thesecond station to buffer data traffic intended for the first station fora first predetermined period; means for granting said request to bufferdata traffic; means for causing the first station to enter a first powersave mode for the first predetermined period; and means for enabling thesecond station to buffer data traffic intended for the first station forthe first predetermined period.
 30. A machine-readable medium comprisingstored instructions, which, when executed by a processor cause theprocessor to implement power saving in an ad-hoc network having aplurality of stations, said instructions comprising: instructions fordetermining whether a first one of the stations has a capability tobuffer data traffic intended for a second station; instructions forrequesting the at least one station to buffer data traffic intended forthe second station for a first predetermined period; instructions forgranting a request to buffer data traffic intended for the secondstation; instructions for causing the second station to enter a firstpower save mode for the first predetermined period; and instructions forenabling the first one station to buffer data traffic intended for thesecond station for a second predetermined period; instructions forcausing the second station to exit the first power save mode after thefirst predetermined period elapses; and instructions for sending thebuffered data traffic to the second station.